In an effort to reduce dependence on fossil fuels, as well as develop transportation that utilizes clean energy, several organizations have attempted to build aircraft that relies on solar power and graphene to get in the air.

Solar Impulse, a long-range experimental solar-powered aircraft project, recently landed in Japan after bad weather grounded its attempt to fly from China to Hawaii on solar power alone.

The Solar Impulse project hopes to complete the first circumnavigation of Earth by a piloted fixed-wing aircraft using only solar power. Its website states that the entire structure is “proportionately 10 times lighter than that of the best glider,” in order to allot room for its batteries as well as a cockpit in which a pilot can live for a week. In the end, it is of the weight of a small van: about 5,000 lbs.

Nanotechnology researchers from Nankai University in China have theorized about graphene being used for solar-powered spacecraft. Their research paper, “Macroscopic and Direct Light Propulsion of Bulk Graphene Material,” explores the idea of “graphene sponges” being used to conduct electricity and heat. According to the researchers, graphene absorbs laser energy and builds up a charge of electrons — when the graphene cannot hold anymore the extra electrons are released, pushing the sponge in the opposite direction.

The paper states that “our results demonstrate that macro graphene based objects could be propelled by a Watt level laser and even sunlight directly up to the sub-meter scale following a novel LIEE mechanism. The propulsion could be further enhanced by increasing the light intensity and/or improving the illumination area. For example, using an adjustable laser array, the force needed for attitude control and orbital adjustment of a spacecraft, and even transporting a payload in outer space could be achieved using light directly.”

The researchers say that graphene sponge could be used to make a light-powered propulsion system for spacecraft that would defeat solar sails. However, The Planetary Society (under CEO Bill Nye “the Science Guy”) is developing its own solar sail program. Solar sails use the sun’s energy as a method of propulsion —“flight by light.” Once in space, LightSail’s solar arrays swing open, revealing the inside of the spacecraft. Four tape measure-like metal booms slowly unwind from storage, unfolding four triangular Mylar sails. Each sail is just 4.5 microns thick — a quarter of the thickness of an average trash bag.

A May 30 press release from The Planetary Society states that the organization’s LightSail spacecraft had a “successful launch into orbit aboard a United Launch Alliance Atlas V rocket out of Cape Canaveral.” The craft went silent after two days of communications, but the test mission “has now resumed contact after a suspected software glitch affected communications. The LightSail team will soon determine when to attempt deployment of the spacecraft’s Mylar solar sails.”

Meanwhile, a “quantum airplane” envisioned by Spanish designer Oscar Viñals could be the future of air travel. The plane, which Viñals says could be a reality by 2030, is designed to improve the physical characteristics of the commercial airplane and reduce its environmental impact.

The Progress Eagle aircraft would eschew fossil fuels, instead depending on six hydrogen engines to get it off the ground. It would be equipped with a rear engine that doubles as a wind turbine, and solar panels on the roof and wings.

The craft would be “equipped with smart- and self-repairing skin’s wings, composed by carbon nanotube and carbon fibers, meta-materials in hexagonal pattern on the surface, and a hollow endoskeleton in an ultra-lightweight beehive-shaped of titanium and graphene; using the graphene material like a micro-supercapacitors (fast electrical storage that can charge and discharge a hundred to a thousand times faster than standard batteries) and as a reinforce of [the] inside’s wing structure.”

^{The AWWA·QG “Progress Eagle” concept plane was “born” like his brother the AWWA·VA “Sky Whale” with the same airplane’s concept, designed for improving the physical characteristics of the commercial airplane and reducing the environmental impact.}

However, Viñals told BBC that this is still a dream, rather than reality. “Today we have about 40% of the technology needed to build it,” the article says. Not only does this technology need to be built, but it also needs to be demonstrated as safe. Aircraft may very well be cleaner, more comfortable, and quieter in the future, but more research is needed before we get there.